[gate-users] Image Reconstruction of Gate output

[Nehmeh, Sadek/Medical Physics]

Dear Theodore and Long,

Yes I'm back, and sorry for taking me time replying to your emails.
Long, I think what you have suggested in your previous email regarding
evaluating the sinogram binner for the DST, and try to incorporate it
with GATE, is a great idea. Meanwhile, I am also testing that for the
DST configuration. Hopefully I will get back to you tomorrow with my
feedback.

Theodore, for your NEMA measurements, I know O. Mawlawi at M.D. Anderson
did the NEMA2001 measurements for the DST. It was published in the JNM
(J Nucl Med. 2004 Oct;45(10):1734-42); you may wana refer to that, and
reproduce their analysis method, for comparison.


	Cheers,

	Sadek

 

-----Original Message-----
From: gate-users-bounces at lphe1pet1.epfl.ch
[mailto:gate-users-bounces at lphe1pet1.epfl.ch] On Behalf Of Mutanga
Theodore
Sent: Monday, January 03, 2005 11:30 AM
To: Long ZHANG; GATE feedback and helpline for Users
Subject: Re:RE: [gate-users] Image Reconstruction of Gate output

Hi Long,
it seems Sadek is back, have you written to him about the code ?

Cheers

Theodore

By the way I was simulating the ECAT exact hr+ and I would like to
compare my results with someone Here is what I had for the resolution
measurements , NEMA 2001 !

transverse @ 1cm = 8.3 mm
axial @1 cm 11.5 mm


transverse radial @ 10cm = 10.59mm
transverse tangential@ 10cm = 10.66mm

axial @10cm 10.31 mm


I wish to find out from the GATE users if these look reasonable, I was
planning to do measurements myself on the ecat but I dont have acceess
to one since initially I was simulating the DST. Also in the NEMA 2001
there is no mention about matrix size for reconstruction , doesnt this
affect the resolution ? I did not correct for anythin in the data from
GATE , would it be better to correct for randoms, scatter ect , if so
HOW (using GATE ?)?


Cheers

'Theo

> Dear Kris,
>
> Thank you very much.
>
> It seems that I have mistake the sinogram width (angle position) as 
> sinogram length (view number, or tangential bin number, or 
> displacement position).
> Am I
> right now?
>
> Regards,
>
> Long
>
> In your mail:
>>From:"Kris Thielemans" <kris.thielemans at csc.mrc.ac.uk>
>>Reply-To: GATE feedback and helpline for Users  
>><gate-users at lphe1pet1.epfl.ch>
>>To: "'Long ZHANG'" <zhanglong99 at tsinghua.org.cn>,
>   "'GATE feedback and helplinefor Users'" 
> <gate-users at lphe1pet1.epfl.ch>
>>Subject: RE: [gate-users] Image Reconstruction of Gate output
>>
>>>
>>> BTW, I was pussled by the sinogram width of DST (420 crystal per 
>>> ring). The number 249 is larger than the 420/2 = 210. How can DST 
>>> get the extra LORs of 39? By interpolation? Could this help to 
>>> improve the spatial resolution? Thank you!
>>>
>>Notation: N= num_detectors per ring
>>
>>Why do you think that the max sinogram width is N /2? This is a 
>>hardware choice (recent CTI scanners tend to have sinogram_width=N/2).

>>The 'physical' maximum of LORs in 2D sinograms is (N^2-N)/2 (i.e. all 
>>lines between pairs of detectors, excluding the degenerate cases, and 
>>identifying det pairs ij and ji). The max number of views is N/2 
>>(you'd expect N, but it's halved because of interleaving). So, the max

>>sinogram width is something like (N-1)
>>
>>
>>Kris
>>
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>
>
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